In the research proposed for the upcoming fiscal year the following experimental projects are to be pursued. 1) Continued attempts to manipulate early embryonic activity and sensory experience in order to examine the effects of such manipulations on later behavior and neural development. This will involve primarily pharmacological manipulations with agents known to increase or decrease muscular activity either by blocking neuromuscular transmission (e.g., curare) or by blocking all bioelectric activity in the nervous system (e.g., tetrodotoxin). 2) Completion of a study involving the putative inhibitory neurotransmitter GABA, and the pharmacological antagonists of GABA, picrotoxin and bicuculline. The aim of this study is to determine the age of onset and subsequent ontogeny of behavioral sensitivity to these agents. 3) Examination of various drugs (e.g., amphetamine) and neurotoxic agents (e.g., 6-OHDA) which are known to act on aminergic neural systems in adult animals. Specifically, this will involve behavioral, biochemical and histological studies of chick embryos at different stages of ontogeny. 4) Initiation of behavioral, neuroanatomical and pharmacological studies with fish embryos (B. danio, the Zebra-fish).